Psychrometer



April 1, 1924.

:NVE/won www mmssfs ATTORNEYS Patented Apr. 1, 1924.

UNITED STATES ALExANDER G. Moenia, or MILTON, ivrassaonUsETTs PSYCHROMETER.

Application led J'uly 19, 1920. Serial No. 397,205.

To all whom t may concern.'

Be it known that I, ALEXANDER GEORGE MCADIE, a citizen of the United States, and a resident of Milton, in the county of Norfolk and State of Massachusetts, have invented certain new and useful Improvements in Psychrometers, of which the following is a specification.

My invention relates to psychrometers, and a purpose of my invention is the provision of an instrument of this character which quickly and accurately determines the relative and absolute humidities of the atmosphere and the dew-point or temperature at which condensation would occur.

I will describe one form of psychrometer embodying my invention and will then point out the novel features thereof in claims.

In the accompanyin drawings:

Figure 1 is a view s owing in side elevation one form of psychrometer embodying .my invention.

Figure 2 is an enlarged fragmentary detailed view showing one of the thermometers.

Figure 3 is a fragmentary view showing in edge elevation the'instrument shown in the preceding views.

Figure 4 is a fragmentary view showing in side elevation the other thermometer arranged at the opposite side of the rod from the first thermometer.

Figure 5 is an enlar ed detail view showing in side elevation t e cage shown in the preceding views with the lining partly removed.

Figure 6 is a view showing in bottom end elevation the cage shown in Figure 5.

Figure 7 taken on the line 7 7 of Figure 2, and

Figure 8 is a detail view of the counter.

Similar reference characters refer to similar parts in each of the several views.

Referring specifically to the drawings and particularly to Figure 1, R designates a at rod formed of any suitable material such as wood or aluminum and preferably of 102 centimeters in length. This rod R is capable of being bodily rotated about its upper end as a center by means of a handle H rotatably mounted upon a shaft S. The shaft S is associated with 'a re 'stering counter designated generally at K, such counter bein of conventional form and including a af uating dial 15 and a pin 16, the latter ging adapted to engage and actuate a tapper 17 of thebell 18.

Ihe shaft 1 of the handle H has a worm 2 which meshes with and drives the disk or dial 15 when the rod R is swung by means ofthe handle. The disk 15 has 100 teeth on the periphery; upon making the 99th turn of the rod the pin 16 will come into engagement with the tapper rod 3. The 100th turn causes the release of said rod so that the tapper 17 (Fig. 1) strikes the bell 18. -A light spring 4 attached to the rod 3 gives the necessary tension.

As shown in Figures 1,2 and 3, thermometers T and T are carried by the rod R and are capable of longitudinal adjustment thereon by means of rectangular shaped yokes Y which are fixed to the thermometers and sldably embrace the rod so that when set screws W carried by the yokes are moved into engagement with the rod, a locking of the thermometers T and T in any adjusted readily effected.

The thermometer T which I term the wet thermometer, is of conventional form with the exception that its face is provided with specially compiled graduated scales designated at B and B. The scale B constitutes a list of temperatures expressed in kilograds and ranging in the present instance from 900 to 1200 in multiples of 10. VThe scale B is a list of pressures of water-vapor saturation equivalent to the correspondlng number of kilograds, such pressures being expressed in units of force or kilobars and position on the rod can be p ranging in number in the present 'instance from 1 to 130. 1s a transverse sectlonal view The thermometer T, which I term the dry thermometer, is similar in construction to the wet thermometer T and is provided with a temperature scale B also expressed in kilograds. The thermometer T is provided with another scale designated yat B2 which comprises equivalent saturation weights expressed in grams per cubic centimeter of space. These scales B and B2 are of the desired range to secure the necessary comparative readings between the thermometer T and the thermometer T.

As shown in Figures 2 and 3, the bulb of the thermometer T carries a cage designated at G which is formed of foraminous material such as wire screen. As shown in Figure 5, the upper end of the cage G is provided with a tie Wire 19 tor securely attaching the cage to the bar. As shown in Figure G the lowest end ot the cage Gr is inturned to provide an upwardly extending lip Q which is designed Jor the purpose ot' securing an absorbent lining L therein, suoli lining being preferL bly formed of clean linen tree from starch or sizing.

rlheI cage serres to hold the linen trom the thermometer bulb, he tendency ot' the enge being to expand linear y when the inst-rument is in use, rfid thus obviate compressional torce on the bulb. This feature is ot especial value 'when making a frost test, tor at such time the Wet linen would treeze to the bulb and cause an erroneous reading, were it not for the supporting cage. ln expanding lineurly the Cage G en nmds both longitudinally and eirciunterentially so as to keep the wet lining far enough away from the bulb to prevent freezing thereto.

ln operation, the il together i i' lining L is removed trom they bulb ot' thermometer T and dipped into water until the lining is saturated. lt is then sl'ppV en the bulb and tastened by the tie 'wire The readings ot the tiro ther @meters noir noted 'whereupon any desired ventilation by means ot rotation is effected by swinging the rod ll about the shaft S a Center. This may he readily aceomplished by the operato;l gripping the hendle lil and giving a eircul lilit i lir motion to the hand.

the rotation ot the rod R a similar movement olf the tiro thermometers 'll and rl" is lilieuise elleeted, and with the latter adjusted to predetermined positions upon the rod. it Will be clear that by rotatingl the rod at 2i predetern'iined speed a delinite Wind 'velocity is automatically generated, und the oegin ning` and ending ot the moyement ot the air over the lining li is rendered detinite. The r/d ran be swung` either rertieally or horizon ally at any desired speed? such speed oeine determined by the registering` eornter E. ln the present inst the construction and operation of the counter K is such that at the completion of every lOO revolutions ot the rod. 'the pin lo engages the topper 'li si as to etilect n. sounding or the nell iS. The is determined ly the mometers ,trom the top ot the rod or axis ot rotation. s at a distance ot l metre or $39.3 inches. the tliei'mometers when whirled uill 'traif'el in one complete revolution am metres or anoroximately twenty feet. Vi is then only necessary to lrnouv the number ot rotations and the time. to ealeulate the speed ot the Wind. lt is touud that with a little prtetiee a normal rate ot suine/ingr ot LGO revolutions per minute can be obtained. lt desired, a Wat/eh ma,v be used and the number or" seconds counted.

o emrnnne the relativo and absolute wind relocity distance oi" the ther-` humidities and the temperature of saturation or the so-called dew-point. l employ the 'ollon'ing equation:

rszrfr' (TTe) in which p5 is the pressureo'f the water Vapor at saturation. or deW-point-, pc the pressure at evaporation, p the pressure ot the atmosphere expressed in tltlOt) dynes or units ot torce), C a lonstant, T the tempo ature oi the dry bulb expressed in liilograds (lthermometry: lool) degrees), and 'l1 the timiperature ol the u'et bulb.

lllien the wind velocity exceeds 2 metres per second or 5 miles per hour. p@ may be written as die; and tor 'purposes ot quick calculation l regard it as 2025/- u'ithout mater lly ellecting the results. veeauise oit' this formula one can quickly determine. the relatii'e humidity by simply 'elerrine to the values in liilobars as given 'jor dill'erent kilograds. '.lo calculate the relative humidity alter the proper period ot whirling, one reads the temperature ot the yet bulb in ind the eorrespondiircT pressure in lrtm this subtracted ot rence bet-.reen the ten'iperature reatdthe tiro t'lierr-,uimeters and the rela iuunldity is the ratio or this yalue in 's to the lrilobars opposite the dry temture or reading oit the thermometer T. 1e den' pointv or tempera ture ot saturalr i ograd reading opposite the ie Ylfraetitw firing the relative the reading' on Vne seal; eter T lllhen calculat U midity in a room, this dingmultiplied by the oubio me ot space in the room, thus giving the dir/eet freight the air which .must be erapora d in such space und at the partieul pti attire then prevalent to produce satiu'ation. The `lence. bet veel the amount actua vy pres nt and theamount needed tor saturation gives the sat-- uration delioit.

The instrument with sew-e i'elinement can be used to measure the 'worli done in eyapo- 'ation. since this is d proportionel to the iporature. ln tereeasting i'rost` tl' instrument can be ti., lier used as a utathermoineter u'hieli is in instrument used li): pliysieians tor meafilurine the tooling' properties ot the sltin. [i duplicate enge (l is warmed to any dos' Ad temperatforer and slipped on the bulb ot the d thermometer T. The rate oi' tall is then noted. Thus tivo cooling` rates are available', one due to evaporation `with a delinite Wind: and another due to radiation and conyeetion with the same delinite Wind. These rates are helpful in estimating the probable minimum temperzit-ure.

Although I hun# herein shown end nur absolut iidity is the lillogriun reading on the seal;A lli opposite to i ll ot the thermomr tem scribed only one form of psychrometer, it is to be understood that various changes and modifications that may be made herein without departing from the spirit of the invention and the spirit and scope of the ap pended claims.

What I claim is: y

1. A psychrometer comprising a rod, means whereby said rod is supported for rotary movement about a transverse axis, a registering counter associated with the rod, dry and wet thermometers, and means whereby said thermometers are mounted for adjustment longitudinally on said rod.

2. A psychrometer comprising a rod, means whereby said rod is supported for rotary movement about a transverse axis, a registering counter associated with the rod, dry and wet thermometers, means whereby said thermometers are mounted for adjustment longitudinally on said rod, the wet thermometer having a temperature scale expressed in kilograds and a pressure scale expressed in kilobars, and the dry thermom eter having a temperature scale expressed in kilograds and an equivalent saturation weight scale expressed in grams per cubic metre of space.

3. A psychrometer comprising a rod, means whereby said rod is supported at one end for rotation about a transverse axis, a pair of yokes longitudinally adjustable on said rod, dry and wet thermometers carried by said yokes, the wet thermometer including a foraminous cage, and an absorbent lining within said cage and surrounding the bulb of said thermometer.

4. A psychrometer comprising a rod, means whereby said rod is mounted for rotary movement about a transverse axis, and dry and wet thermometers adjustable longitudinally on saidkrod.

5. A psychrometer comprising a shaft, a rod having means for rotatably mounting it on the shaft, a registering counter, gearing incorporated in said rotatable mounting for registering the number of revolutions of said rod when a circular swinging motion is imparted to the shaft, an audible signal associated with the counter, wet and dry thermometers carried by the rod, and means whereby said thermometers are mounted for adjustment longitudinally on said rod.

6. In a psychrometer, a thermometer, a foraminous cage surrounding the bulb of the thermometer, and a lining within the cage formed of absorbent material, the cage expanding linearly and thus obviating comprcssional force on the thermometer bulb.

7. In a psychrometer, a thermometer, a foraminous cage surrounding the bulb of the thermometer, a tie wire carried by the cage for securing the cage to the bulb, a lining within the cage formed of absorbent material, and a lip on the cage Jfor supporting the lining in the cage. v

8. A psychrcmeter comprising a rod, means whereby said rod is supported for rotary movement about transverse axis, a registering counter associated with the rod, dry and wet thermometers, means whereby said thermometers are mounted for adjustment longitudinally on said rod, the wet thermometer n having a temperature scale and a pressure scale, and the dry thermometer having a temperature scale and an equivaient saturation weight scale.

9. A psychrometer comprising a wet bulb, means by which said bulb may be whirled and means for regulating the velocity of air over the bulb in a whirling operation.

l0. A psychrometer comprising a rod, a handle, means by which the rod is revolubly connected to the handle so that the rod may be rotated around the handle, a thermometer carried by the rod, means permitting adjustment of the thermometer between the end of the rod and the axis of rotation at the handle to thereby vary the velocity of an equivalent wind passing the thermometer and means to sound an alarm` at a predetermined number of rotations of the rod to indicate the time of said rotation.

ll. A psychroineter comprising a rod,y a handle having a shaft upon which the rod is revolubly mounted so as to be rotated around the axis of the handle, a thermometer carried by the rod, a foraminous cage carrying an absorbent lining adapted to be dipped in water and thus contain a predetermined amount, means by which the cage is readily attached and detached from the buib of the thermometer, means by which the thermometer may be adjusted along the rod between the end thereof and the axis of the handle and thus vary the velocity of the equivalent wind passing the wet lining, and means associated with the rod and handle for sounding an alarm after a predetermined time of rotation of the rod.

i2. A psychrometer comprising means to be whirled, a wet bulb carried thereby, and means to vary the radial position of the bulb and thereby control the amount of air passing thereover.

ALEXANDER G. MCADIE. 

